System of radio telegraphy and telephony



April 27 1926. 1,582,177

J. H. HAMMOND, JR

SYSTEM OF RADIO TELEGRAPHY AND TELEPHOXY' Original Filed Sept. 25 1917 Patented Apr. 27 1926.

JOHN HAYS HAMMOND, J'R., OF GLOUCESTER, MASSACHUSETTS. I

SYSTEM OF RADIO TELEGRAPHY AND TELEPHONY.

Application filed September 25, 1917. Serial No. 193,139.

To all whom it may concern:

Be it knownthat I, JOHN HAYs HAM+ MOND, Jr., a citizen of the United States, and a resident of Gloucester, in the county of Essex and State of Massachusetts, have invented certain new and useful Improvements in Systems of Radio Telegraphy and Telephony, of which the following is a specification.

Some of the objects of this invention are to provide improved means for the transmission of radiant energy; to provide improved means for the reception of radiant energy; and to provide other improvements as will appear hereinafter.

In the accompanying drawings:

Figure 1 is a diagrammatic representa tion of a transmission system constructed in accordance with this invention;

Fig. 2 is an enlarged, fragmentary, top plan view of the same; 7

Fig. 3 is a diagrammatic representation of a receiving system constructed inaccordance with this invention; and

Fig. 4 is a diagrammatic representation of the waves of electro-radiant energy emitted by the transmission system shown in Referring to the drawings and particularly to Fig.1 1, oneform of transmission system constructed in accordance with-my in vention comprises an open, aerial, transmitting circuit 1, including an upright antenna 2, the lower end'of which is connected to one end of an insulated impedance coil 3. The other end of the coil 3 is connected to one end of a conductor 4 which is grounded.

through an inductance 5 at 6. :The inductance forms the secondary of astep-up transformer 10,-theprimary coil 11 of which is inserted in a closed, oscillatory circuit 12 which includes a variable condenser 13, and which is arranged to he energized by a high frequencyelectric alternator 15 under the control of a switch 16. This alternator 15 is arranged to be'rotated at any desired uniform rate to produce the desired number of alternatlonsm the closed c rcuit 12. For

instance, the alternator 15 may berotated so as to produce 50,000 alternations per second to cause the antenna 2 to emit radiant oscil-' lations accordingly in a well known manner.

For modifying from time to time at the will of an operator the electro-radiant oscillations emitted by the antenna'2 as a result of the action of the alternator 15 upon the closed circuit 12, the'insulated coil 3 is arranged around one portion of an open, rectangular core 20which maybe provided intermittently in synchronism with the operation of the alternator 15, means is provided comprising a battery 25, one pole of ENT omen.

which is connected by a conductor 26 to one end of an insulated coil 27 which surrounds a portion of the core 20. The other end of the coil 27 is connected by a conductor 28 and branch conductor 29 with a brush 30 I 1 which engages a commutator 31. The commutator 31 is also provided with a. second brush 32 which is connected by a conductor 33 to, a fixed terminal 34. The other pole of the battery 25 is connected by a conductor 39 to a switch 40 which is arranged to swing about a pivot 41 into and out of engagement, with the terminal 34 or with a fixed terminal 42 which is connected by a conductor 43 to the conductor 28 leading from one end of the coil 27. The arrangement of the switch 40 and the fixed contacts 34 and 42 is such that when the switch 40 is in engagement with the fixed contact 34 and the commutator 31 is operated, a circuit is intermittently closed through the battery 25, the coil 27, and the commutator, and when the switch 40 is in engagement with the other fixed contact 42,

the commutator 31 is cut out, and the circuit through the battery. 25 is maintained con tinuously closed through the coil 27 and con ductor 43. When the free end ofthe switch 40 is spaced between the two fixed contacts 34and 42, the circuit through the battery 25 and coil 27 is kept open. The parts are preferably so arranged and proportioned that when the circuit is closed through the battery 25 and the coil 27, the core 2O will be magnetizedup to the point of satur ation. For convenience of description, the core 20 with the parts immediately cooperating therewith may be referred tohereinafter as the wave-modifying device 45.

b The commutator 31 may be constructed in any suitable manner tointerrupt the current from the battery 25 through the coil 27 momentarily and intermittently at any desired rate when the switch 40ris in engages ment with the fixed contact 34. For in stance, as shown in Fig. 2, the commutator 81 may consist of a cylindrical body portion 50 driven by a shaft 46 connected with the alternator 15. The body portion 50, as shown, is made of insulating material and is provided with a continuous ring 51 of conducting material arranged to be engaged by the brush 30 and with an annular series of spaced, conducting segments 52 arranged to be engaged successively by the brush the ring 51 and the conducting segments 52 being rigidly secured to the body port on 50, and the conducting segments 52 being electrically connected to the continuous conducting ring 51 by conductors 53. The spaces between the conducting segments 52 are uniform in width and of such a width that the corresponding brush 32 will momentarily break the circuit through the battery 25 each time that one segment 52 is moved out of engagementwith the brush 32, the next segment 52 being immediately thereafter moved into engagement with the brush 32. x 1m While the commutator just described s one form of interrupter that may be used, itis to be understood that any suitable form of interrupter may be en'iployed in the place of the above described commutator. For instance, it has been found that a rapidly revolving jet of mercury described by Max Levy in the Elektrotechnische Zeitschrift of October 12, 1899, Vol. 20, page 717) can be used as a high frequency inter rupter for electrical currents, or any other suitable form of interrupter may be so applied. V

In the operation of the transmission system shown in Fig. 1, with the switch 10 closed, the switch 40. closed upon the finer contact 42, and the--al'ternator 15 in oper ation at a rate, for instance, of 50,000 alternations per second, corresponding oscillations will be set up in a well known manner in the closed, oscillatory circuit 12 which will induce corresponding oscillations in the open, aerial circuit 1 and will thereby cause the antenna 2 to emit corresponding, sinusoidal, electro-radiant oscillations substantially in the form shown by the full curved line of Fig. 1-, this curved line 75 being plotted upon the straight line 76 indicating zero potential.

As long as the switch 4&0 remains in enagement with the fixed contact -12, and the core 20 is consequently magnetized up to its point of saturation, thecore 20 will have practically very slight if any damping or other effect upon the radiant oscillations emitted by the antenna 2; but when the circuit is broken through the battery 25 and the coil 27, thus permitting a demagnetiza tion of the core 20, the permeability of the core to the magnetic field produced by the alternations in the impedance coil 3 will be mean? thus rapidly and largely increased, and this magnetic field will react upon the coil 3 in a well known manner to suddenly dampen, choke or reduce the amplitude of the alternations in the coil 8 and antenna 2. Consequently, the amplitude of the electro-radiant oscillations emitted by the antenna 2 will be reduced. (hen the switch 10 is in engagement with the fixed contact 34, thus closing the circuit from the battery 25 through the coil 27 and commutator 31, the damping effect upon the amplitude of the electroradiant oscillations emitted by the antenna 2 will occur periodically at a rate predetermined by the construction and arrangement of the commutator 81 or other interrupter, which are preferably such that the circuit through the battery 25 and coil 27 is momentarily opened at each peak of the electric alternations or oscillations in the open, aerial circuit 1. Consequently, the commu tator 31 produces an intermittent damping or reduction in amplitude of the electroradiantoscillations radiated by the antenna 2, such damping occurring at each peak of the oscillations radiated as indicated by the curved, broken lines 78 of Fig. 4-. l

t is evident from a consideration of the wave form shown in Fig. f that, when the wane-modifying device 15 is operating through the action of its commutator 31, there exists in the antenna 1 of Fig. 1 what may be considered as a double frequency phenomenon. It is evident that there 18 a sinusoidal, periodic alternation of the current produced in the radiating system by the alternator 15 of Fig. 1. This periodic, alternating current of approximately sinusoidal form is represented by the graph 7 The frequency of this alternation, as hereinbefore mentioned, is, in this particular case, 50,000 cycles per-second. There is also produced in the sinusoidal wave form of the radiating current an amplitude variation effect producing a depression 7 8 at each peak of the alternating current represented by the graph 7 5. There therefore exists an amplitude variation in the radiating system of approximately double the frequency of the fundamental frequency induced therein by the high frequency alternator. The arrangement is such that although the amplitude variation effect 78 occurs only twice in the cycle at the transmitting station, the variations in the receiving circuit, which will follow the dotted line of Fig. rectified, will comprise uni directional pulsations at the rate of 150,000 per second.

One form of receiving system constructed in accordance with this invention is shown in Fig. 3, and comprises an aperiodic or untuned receiving antenna 100 coupled 'hrough the primary winding 101 of a highfrequency oscillating transformer 103 to the secondary winding 104 of the said oscillating transformer. The .inductive winding 104 comprises part of an oscillatory circuit 105 containing a suitable variable condenser The said oscillatory circuit 105 is aperiodic so as to respond to the coexisting frequencies emitted by the sending station of Figure 1 and is arranged to control any suitable detector, for instance, a detector 107 of the gaseous or electronic type comprising a bulb 108 containing a vacuous space and having therein a grid 109, a cathode 1 10 and an anode 111. The manner of operation of said detector is well known in the art. The detector 107 controls a circuit 115 containing a battery 113 and an inductance 114;. It is understood that the current from the battery 113 normallyv flows through the detector 107 through the action of the electronic discharge from the filament 110 which is heated by a battery 112. WVith the variation of potential induced on the grid.109 through the alternating currents present in the oscillatory circuit 105, the current'from.

battery 113 flowing through the detector 107 is alternately increased and decreased in specific phase relation to the alternating current/present in circuit 105 which induces specific potentials in grid 109. Thus if the detector 107 be highly evacuated it wlll possess but little hysteresis effect and will allow in its valve action upon the current of battery 113 a modification of said battery current simulating closely the 1110611- fications taking place in the alternating current in oscillatory circuit 105. The detector 107 may, thereforefbe considered as a repeating device.

there are two coexistent frequencies in the wave form as shown. Moreover, inasmuch as the detector 107 is essentially a repeating device and an amplifying device, it'will be understood that the current from the battery 113 passing through the inductance 114 and through the detector 107 will approximate closely in its amplitude variation the wave form shown in Fig. 4; that is to say, there will coexist in the circuit 115 the wave form shown in full lines in Fig. 4 and another wave form of triple frequency due to the wave form 75 having been modified as indicated by the broken lines 78. Coupled to the oscillatory circuit 115 bya transformer having the inductance 11 1 as its primai'y winding and a secondary winding 116 is an oscillatory circuit 118. Said oscillatory circuit 118 comprises a variable condenser 117 and controls in a well known manner a detector 119 of any suitable .form but preferably of the gaseous or electronic type.

The oscillatory circuit 118 is tuned to approximately triple the frequency of the alternator 15. The alternating currents produced in the oscillatory circuit 118 create periodic rises of potential on the grid 120 of the gaseous detector 119 and therefore modify the current of battery 121 flowing through detector 119 through the electronic discharge from cathode 122 heated by battery 123 to the anode 1241. In the circuit 125 containing the battery 121 and the telephone 126 and the circuit breaker 127, there would normally exist unidirectional pulses of current having a frequency of 150,000 per second. On account of the inertia of the diaphragms of the said telephone 126, no sound would be produced by the pulsations of current in said circuit 125 unless the circuitbreaking mechanism 127 were caused to. function. Said circuit-breaking mechanism 127 may resemble any suitable form of cir cuit breaker as shown by me in Fig. 2, with the difference that the rate of interruption.

of the current in this instance is much lower. Forexample, it may be 1,000 breaks per second. Thus the unidirectional pulsations of current of 150,000 per second frequency in traversing the circuit 125 and the circuitbreaking mechanism 127 are broken into comprisingan oscillatory circuit 129 in- Now referring to Fig. 4, it s seen that ductively coupledby a suitable transformer 128 to the oscillatorycircuit 118 and energized by a suitable high frequency alternator 130 at'the rate of 151,000 alternations per second, or other suitable number of alternations. If the frequency of the high frequency alternator 130 be at the rate of 151,000 alternations per second, periodic amplitude variations orbeats of electrical current of a frequency of 1,000 per second will be produced in the oscillatory circuit 118. Thus in circuit 125, there would be produced pulsations of current at the rate d of 1,000 per second which would produce in the telephones 126 the desired high pitched note. In the use of a separate alternating the switch 16 or of a second switch or key which those skilled in the art will have no difticulty in providing in the arrangement shown in Fig. 1 in a usual or suitable manner. Likewise, if it is desired to employ the invention in telephony, those skilled in the art can readily provide a telephone transmitter in proper relation to the other parts of the transmitting arrangement shown in Fig. 1.

One of the advantages of this invention is that it provides in the receiving system a double selectivity from extraneous interference through the conjoint action of two receiving circuits having widely different periodicities but operating successively to regis ter signals. Thus any interfering waves having a periodicity sufficiently close to the first receiving circuit to force the same into oscillations would be unable to force the second circuit whose periodicity varies greatly from that of the interfering wave.

Another advantage obtained is the advantage of secrecy of transmission of messages. The ordinary system now in use is only capable of receiving the wave form represented by graph in Fig. 4, whereas my system is only responsive to the modified wave form shown in graphTS of Fig. Thus, by the employment of this improved system of wave transmission and reception, it is possible to secure secrecy and immunity from interference from the present type of radiotransmission systems.

\Vhile I have shown specifically a ratio of frequencies in the wave forms shown in Fig. 4 of 1 to 3, it is obvious that the ratio may be varied by variation of the speed or construction of the commutator 31 of Fig. 2 and by correspondingly changing the tuning of the circuits of the receiving system.

It is to be understood that this invention is not limited to the specific. system herein disclosed, but might be embodied in various systems without departing from the spirit of the invention or the scope of the appended claims.

-I-Iaving thus fully described my invention, I claim:

' 1. In a system for the transmission of energy, the combination with means for producing a series of electric oscillations, of means operative during a predetermined portion of each half cycle of each oscillation.

only to vary the amplitude of each of said oscillations in a uniform manner.

2; In a system for the transmission of energy, the combination with means for generating a series of electrical oscillations, of means operative during a predetermined portion of each half cycle of each oscillation only to impress upon each of said oscillations a plurality of intermittent amplitude variations.

3. In a system for the transmission of energy, the combination with means for pro ducing a series of electric oscillations, of means operative to momentarily vary the amplitude of each of said oscillations in a uniform manner and means for receiving said oscillations and variations including cooperating elements tuned to the frequency of said oscillations and the frequency of said variations respectively.

4:. In a system for the transmission of energy, the combination with means for gene-rating a series of electrical oscillations of means operative to impress upon each of said oscillations a plurality of intermitting amplitude variations, and means for selectively receiving said oscillations and said variations including cooperating elements tuned respectively to the frequency of said oscillations and the frequency of said variations. r

5. In a system of radio transmission, the combination with means for generating a series of electro-radiant oscillations having a predetermined frequency, of means for periodically varying the amplitude of said oscillations respectivei' the amplitude of each oscillation being varied only during a total amount of time appreciably less than the total duration of said oscillation.

6. In a system of radio transmission, the combination with means for generating a series of electro-radiant oscillations having a predetermined frequency, of means for repeatedly modifying the amplitude of each of said oscillations at a predetermined frequency greater than said first-mentioned frequency, and means for receiving said oscillations and said variations including cooperating elements tuned respectively to said frequencies.

7. In a system for the transmission of radiant energy, the combination with means for transmitting a series of electro-radiant oscillations normally having a sinusoidal form, of means operative to vary the form of each of said oscillations during only aportion of each half cycle of each oscillation.

8. In a system for the transmission of radiant energy, the combination with means fortransmitting a series of electro-radiant oscillations normally having a sinusoidal form, of means operative to vary the form of each of said oscillations and means for receiving said oscillations and variations including cooperating elements tuned respectively to the frequency of said oscillations and to the frequency of said variations.

9. In a system for the transmission of radiant energy, the combination With anaerial circuit including a coil, of means operative to cause said circuit to emit electroradiant oscillations, and means for periodically varying the amplitude of said oscillations including an electro-magnetic core arranged to control said coil, and means synchronized with said first mentioned means for intermittently magnetizing said core. I

10. In a system for the transmission of radiant energy, the combination with'an aerial circuit including acoil, of means operative to cause said circuit to emit electroradiant oscillations, and means for periodically varying the amplitude of said oscilla ing said core. I

11. A system for the transmission of elec tric energy comprising acircuit, means for producing electric oscillations in said circuit, and means automatically operative to vary the amplitude of each half-cycle of said oscillations during a time less than the time period of the respective half-cycle.

12. The method for the transmission of electric energy which consists in producing a series of electro-radiant impulses, producing in sald lmpulses a series of periodic variations having a frequency not less than the frequency of said impulses, and receiv' ing said impulses and variations upon'two cooperating elements tuned to the frequency of said impulses and the frequency of said variations, respectively.

13. The method of transmitting electric energy which consists in generating periodic electric impulses producing in said impulses a'series of periodic variations having a frequency not less than the frequency of said impulses, selectively receiving said impulses and variations, and cansing the operation of a receiving device as a result'of a conjoint action of said impulses and variations.

14. A system for transmitting electric energy comprising means for producing periodic electrical impulses, means for producing in said impulses a series of periodic variations having a frequency not less. than the frequency of said impulses, andmeans for receiving said impulses and variations comprising two cooperating elements tuned to respond to saidimpulses and said variations, respectively.

' 15. In a system for the transmission of energy the combination with a circuit including a coil, of means operative to produce electrical oscillations in said circuit, and means for varying the amplitude of said oscillations periodically including a magnetizable'core arranged within the influence of said coil and means automatically operative in synchronism with said oscillations to magnetize said core'during predetermined portions of said oscillations.

16.111 a system for producing oscillations the combination with a circuit including a coil, of means operative to produce electrical oscillations ill Said circuit and means automatically operative to vary said oscillacore surrounded'by said coil, and means for intermittently magnetizing said core including a circuit arranged to influence said core and means for energizing said circuit in synchronism with said oscillations during mg saturation of the core to impress amplitude variations upon said pulsations.

18. A signaling system compr sing a transmitting circuit, a saturable core, means for producing periodic waves in said circuit,

and means actuated in, synchronism with -Stll producing means for intermittently causing saturation of the core to impress amplitude variations on said waves.

19. A radio system comprising a transmitting circuit, a saturable core, means including an alternator for producing periodic waves in said circuit, and means actuated in synchronism with said alternator for causing saturation of the core to impress amplitude variations on each of said waves. 20. A signaling system comprising a transmitting circuit, a saturable core, means including a source of electrical oscillations for producing periodic waves in said circuit, and means actuated in synchronism with said source for causing saturation of the core to impress amplitude variations on each half cycle of each of the oscillations.

21. A signaling system comprising a transmitting circuit, a saturable core, means tion with a source of high frequency elec-- trical oscillations; of a saturable core having a wmdlng arranged to vary the amplitude of the-oscillations, and means for causing said core to be saturated during predetermined portions of the oscillations.

23. In a transmitting circuit for a radio system, the combination with a source of electrical oscillations; of a saturable core having a winding arranged to vary the amplitude of the oscillations, and means for saturating said core in synchronism with the active periods of said source and effective only during predetermined portions of the periods.

24. A method of signaling which consists in generating a series of waves of a predetermmed frequency having impressed theretions periodically including a magnetizahle in a series of variations of a higher frequency, and selectively receiving the energy of said waves and variations upon co-operating receiving elements, one of which is responsive to the combined energy of said waves and variations, and the other of which is responsive only to said variations.

25. A method of signaling which consists in generating a series of waves of a predetermined frequency having impressed therein a series of variations in amplitude of a higher frequency, and selectively receiving the energy of said waves and variations in amplitude upon cooperating receiving elements, one of which is responsive to the combined energy of said waves and variations in amplitude, and the other of which is responsive only to said variations in amplitude.

26. A signalling system comprising a circuit, means for producing electrical oscillations in the circuit, and means for producing in said oscillations a frequency component of a harmonic of the fundamental frequency of the oscillations, said means comprising a core of magnetic material having a winding connected in said circuit, a second circuit including a source of direct current, winding operatively connected with the magnetic core and means for interrupting thefiow of direct current in the last-menti-oned circuit, and means for operating the interrupting means in synchronism with the means for producing the electrical oscillations.

27. A signalling system comprising a circuit, means for producing electrical oscillations in the circuit and means for producing in said oscillations a component of a fre quency equal to three times the fundamental frequency of the oscillations, said means comprising a core of magnetic material, a winding in said circuit under the influence of the core, a second circuit including a source of direct current, a winding operatively connected with the magnetic core and means for interrupting the flow of direct current in the last-mentioned circuit, and means for operating said interrupter in synchronism with the means for producing the electrical oscillations to magnetize the core at periods corresponding with the peaks of the oscillations.

28. A method of wireless signalling which includes the steps of producing electrical oscillations, transmitting energy derived from said oscillations and having a fundamental frequency component and a frequency component equal to a harmonic of the fundamental frequency, modulating the transmitted energy in accordance with signals, and utilizing both of said frequency components in receiving the transmitted energy.

JOHN HAYS HAMMOND, J n. 

